The number of marks is given in brackets [ ] at the end of each question or part question.

Transcription

1 EXAMINATIONS COUNCIL OF SWAZILAND in collaboration with UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE Swaziland General Certificate of Secondary Education * * COMBINED SCIENCE 6886/02 Paper 2 (Core) October/November hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. Write your answers in the spaces provided on the question paper. A copy of the Periodic Table is printed on page 20. You may use a calculator. The number of marks is given in brackets [ ] at the end of each question or part question Total This document consists of 17 printed pages and 3 blank pages. DC (NF/CGW) 52341/3 [Turn over

2 1 (a) Fig. 1.1 shows part of the human nervous system. 2 Fig. 1.1 On Fig. 1.1, label the two parts of the central nervous system. [2] (b) (i) Explain what is meant by the term homeostasis.... [2] Ice cream contains a lot of sugar. Describe how the human body keeps the blood sugar constant after eating ice cream.... [4]

3 2 Fig. 2.1 shows the deflection of alpha, beta and gamma radiations in an electric field. 3 radioactive source A B C Fig. 2.1 (a) Name the radiations A, B and C. A... B... C... [3] (b) State two dangers of the radiations to living organisms [2] (c) State one use of gamma radiation.... [1] [Turn over

4 3 Hydrogen chloride (HCl) and sodium chloride (NaCl) are common compounds of chlorine. 4 (a) (i) Using dots and crosses, complete Fig. 3.1 to show the bonding in a hydrogen chloride molecule. H Cl Fig. 3.1 [2] Name the type of bonding that occurs in HCl. (b) Explain why NaCl would have a very high melting point.... [1] 4 Bobo places a thermometer, which is at room temperature, near a lit Bunsen burner, to measure the temperature of the air. (a) State what happens to the liquid in the thermometer.... [1] (b) Bobo decides to paint the bulb of the thermometer black. He puts it at the same distance from the lit burner as in (a). State and explain what he observes [2]

5 5 (a) Fig. 5.1 shows two types of blood vessels A and B. 5 A B Fig. 5.1 (i) State two visible differences between blood vessel A and blood vessel B [2] Explain how the structure of blood vessel B is adapted to its function.... [2] (iii) State the nature of blood that is found in blood vessels similar to blood vessel A. (b) Plants absorb water from the soil and transport it to other parts through vessels. (i) Name the vessels that transport water from the roots to the leaves. Explain the process by which root hair cells absorb water from the soil.... [2] [Turn over

6 6 (a) Ethanol, C 2 H 5 OH, can be used as a fuel. 6 (i) State two other uses of ethanol [2] Draw the structural formula for ethanol. [2] (b) Fig. 6.1 shows a hydrocarbon. H H H H C C C H H Fig. 6.1 (i) Name the hydrocarbon shown in Fig Name the homologous series to which the hydrocarbon belongs. (iii) Name the compound with two carbon atoms in this homologous series.

7 7 (c) Methane is a hydrocarbon that is used as fuel. When methane burns, it reacts with oxygen. (i) Construct a word equation for the reaction of methane with oxygen. Name this type of reaction. [Turn over

8 7 Fig. 7.1 shows a pendulum that swings between A and C. The bob takes 1.25 seconds to move from A to C. 8 bob A C B (a) Calculate the period of the pendulum. Fig [1] (b) The bob has a mass of 62.0 g and a volume of 5.5 cm 3. Calculate the density of the pendulum bob. State the formula that you use and show your working.... [3]

9 (c) The total length of the arc path ABC followed by the bob as it swings is 40.0 cm. 9 Calculate the average speed of the bob as it swings from A to C. State the formula you use and show your working.... cm / s [3] [Turn over

10 8 (a) Fig. 8.1 shows a calendar for April and May. Thuli s menstruation days for April are shaded. 10 April Sun Mon Tue Wed Thu Fri Sat May Sun Mon Tue Wed Thu Fri Sat Fig. 8.1 (i) How long did Thuli s menstruation last? Circle the day when ovulation is likely to occur in May. [1] (iii) Shade the days when Thuli s next menstrual period is likely to occur. [1] (iv) Describe the process of menstruation.... [2]

11 (b) Fig. 8.2 shows a human foetus. 11 A B C Fig. 8.2 (i) Identify the structures B and C. B... C... [2] Describe two functions of structure A [2] [Turn over

12 9 Fig. 9.1 shows a circuit with a battery, a variable resistor and two lamps, L 1 and L 2, connected in series. 12 6V L 1 L 2 Fig. 9.1 L 1 has a resistance of 15 Ω and L 2 has a resistance of 25 Ω. (a) Calculate the combined resistance of L 1 and L Ω [1] (b) The variable resistor is set to zero resistance. Calculate the current in the circuit. State the formula that you use and show your working.... [2] (c) The resistance of the variable resistor is now increased. State what happens to the brightness of the lamps.... [1]

13 (d) The lamps each have a filament that emits light when current passes through it. 13 (i) Name a material suitable for the filament. Name a form of energy given out by the lamps, other than light. (e) State two hazards of damaged insulation around a mains electric cable [2] [Turn over

14 10 (a) A list of gases is shown in the box below. the gases in the box to answer the following questions. You may use any of the gases once, more than once, or not at all. 14 acetylene ammonia carbon dioxide ethane hydrogen nitrogen propane Name a gas that (i) is approximately 79% by volume of air, burns in oxygen to form carbon dioxide and water only, (iii) is used in welding. (b) Ammonia is used to make fertilisers. The use of fertilisers improves crop production. (i) Name three essential elements present in many fertilisers [3] Name two compounds that are commonly used as fertilisers [2]

15 11 Fig shows an object in front of a mirror. 15 object mirror observer Fig On Fig draw an accurate diagram of the image of the object seen by the observer in the mirror. [3] [Turn over

16 12 (a) Thoko investigates the reaction of four metals P, Q, R and S, with dilute hydrochloric acid and water. 16 The following are the results she obtained. P Q R S reacts with steam but not with cold water. reacts with dilute hydrochloric acid but not with steam or cold water. reacts quickly with cold water. does not react with dilute hydrochloric acid or with water. (i) Arrange the metals P, Q, R and S in order of their reactivity, starting with the most reactive. most reactive least reactive... [2] Identify one metal from P, Q, R and S which could be used to make cooking pots. Suggest a reason for your answer.... [2] (iii) Suggest which of the metals P, Q, R and S could be copper. (b) Magnesium is a metal and carbon is a non-metal. State two physical differences between carbon and magnesium [2]

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20 20 DATA SHEET The Periodic Table of the Elements Group I II III IV V VI VII H Hydrogen 2 4 He Helium 3 7 Li Lithium 4 9 Be Beryllium 5 11 B Boron 6 12 C Carbon 7 14 N Nitrogen 8 16 O Oxygen 9 19 F Fluorine Ne Neon Na Sodium Mg Magnesium Al Aluminium Si Silicon P Phosphorus S Sulfur Cl Chlorine Ar Argon K Potassium Ca Calcium Sc Scandium Ti Titanium V Vanadium Cr Chromium Mn Manganese Fe Iron Co Cobalt Ni Nickel Cu Copper Zn Zinc Ga Gallium Ge Germanium As Arsenic Se Selenium Br Bromine Kr Krypton Rb Rubidium Sr Strontium Y Yttrium Zr Zirconium Nb Niobium 96 Mo Molybdenum Tc Technetium Ru Ruthenium Rh Rhodium Pd Palladium Ag Silver Cd Cadmium In Indium Sn Tin Sb Antimony Te Tellurium I Iodine Xe Xenon Cs Caesium Ba Barium 139 La Lanthanum 57 * Hf Hafnium Ta Tantalum W Tungsten Re Rhenium Os Osmium Ir Iridium Pt Platinum Au Gold Hg Mercury Tl Thallium Pb Lead Bi Bismuth 84 Po Polonium 85 At Astatine 86 Rn Radon Fr Francium Ra Radium 227 Ac Actinium 89 * Lanthanoid series Actinoid series Key b a X a = relative atomic mass X = atomic symbol b = atomic (proton) number Ce Cerium 232 Th Thorium 141 Pr Praseodymium Pa Protactinium Nd Neodymium 238 U Uranium Pm Promethium Sm Samarium Eu Europium Gd Gadolinium Tb Terbium Dy Dysprosium Np Neptunium 94 Pu Plutonium 95 Am Americium 96 Cm Curium 97 Bk Berkelium 98 Cf Californium Ho Holmium Es Einsteinium Er Erbium Fm Fermium Tm Thulium Md Mendelevium Yb Ytterbium No Nobelium Lu Lutetium Lr Lawrencium 103 The volume of one mole of any gas is 24dm 3 at room temperature and pressure (r.t.p.).